Although there can be genetic and physiological causes for early puberty, scientists have pointed to environmental chemicals as one of the culprits of this new normal. Estrogen-mimicking chemicals are used in processed foods and containers, which can leak out, thus contaminating the product they hold. According to The Times, studies on animals show that when exposed to some chemicals their bodies can mature early, especially when these chemicals mimic estrogen in our bodies, which can alter the timing of puberty.